Simultaneously detecting the power of two different polarization components is important for some sensor and measurement applications, such as certain radar applications. A pigtailed polarization beam splitter coupled with two separate photodetectors can be used for such applications. However, this arrangement is generally bulky, troublesome to handle, and costly.
Integrating polarization-splitting components with photodetectors in a common housing (package) allows a more compact polarization diversity detector (PDD) to be created. A known PDD is a single channel fiber-coupled PDD that utilizes discrete components comprising a polarization beam splitter which splits a randomly polarized beam into two orthogonal, linearly polarized components. S-polarized light is reflected at a 90 degree angle (right angles) by the polarization beam splitter while P-polarized light is transmitted. The 90 degree spread in the respective polarized light output by this PDD facilitates the positioning of separate photodetectors needed to independently detect the respective polarized beams with sufficient clearance between the respective polarized beams. Such PDDs can provide fairly good detection sensitivity, extinction ratio, and reliability, as well as a relatively small size and low cost.